The phase equilibrium of the binary system (CO2 + propionic anhydride) was determined experimentally at temperatures of 308, 313, and 323 K and pressures up to 10 MPa. Measurements were carried out in a high-pressure visual cell with variable volume. The experimental data were modeled using the Peng-Robinson equation of state and the Mathias-Klotz-Prausnitz mixing rule. A good correlation was achieved with this model, with a total average absolute deviation of 0.21%.